a. Field of the Invention
In general, the present invention relates to storage facilities, and especially the bulk storage of granular and/or powdered materials. More particularly, the present invention pertains to promoting mass flow when unloading the storage facility: by minimizing common bulk storage problems such as bridging, coring, arching and ratholing; and by creating a more effective flow pattern within the storage facility. Reduction of the forces associated with the stored material in the vicinity of the discharge port also contributes to the effectiveness of the system.
b. Description of Related Prior Art
Numerous past attempts have been made at improving the unloading of particulate material stored in bulk storage facilities. As a result of many factors including heat, weight, pressure and moisture, stored particulate matter such as grain or powder often compacts and agglomerates, for example, along the side walls of a storage facility thereby creating static zones, and detrimentally effecting the unloading of the storage facility. These static zones of material, in combination with bottom unloading of the material through a discharge port, often produces a funneling or ratholing effect causing and maintaining the separation of the material ingredients and the incomplete purging of the storage facility. The introduction of new material into the bulk storage facility can consequently establish an undesirable last-in, first-out flow pattern.
Of the above-discussed storage problems, perhaps the most common is a phenomenon known as "bridging" whereby a natural arch of material forms over the discharge opening, which arch has sufficient strength to hold back the material remaining in the storage facility and prevent it from flowing through the exhaust port.
Another significant problem with the unloading of granular and/or powdered material from a bulk storage facility results from the weight forces of the material acting at the point of discharge. It is not uncommon, for example, for a bulk storage facility to be directly coupled to a material transport system for carrying the material away from the bulk storage facility by use of an auger, conveyer belt, etc. Concentration of the material weight forces at the transport system entry, however, greatly increases the power required to drive the auger, conveyor belt, etc. In addition, the material weight forces can result in clogging the system, or causing some other malfunction.
In severe cases, the forces associated with any or all of the above-discussed material storage problems have caused vibration, deformation and even collapse of the bulk storage facility.